Buggy code:
public class SampleResultConverter extends AbstractCollectionConverter { private static final String JAVA_LANG_STRING = "java.lang.String" ; private static final String ATT_CLASS = "class" ; protected static final String TAG_COOKIES = "cookies" ; protected static final String TAG_METHOD = "method" ; protected static final String TAG_QUERY_STRING = "queryString" ; protected static final String TAG_REDIRECT_LOCATION = "redirectLocation" ; protected static final String TAG_REQUEST_HEADER = "requestHeader" ; protected static final String TAG_RESPONSE_DATA = "responseData" ; protected static final String TAG_RESPONSE_HEADER = "responseHeader" ; protected static final String TAG_SAMPLER_DATA = "samplerData" ; protected static final String TAG_RESPONSE_FILE = "responseFile" ; private static final String ATT_BYTES = "by" ; private static final String ATT_DATA_ENCODING = "de" ; private static final String ATT_DATA_TYPE = "dt" ; private static final String ATT_LABEL = "lb" ; private static final String ATT_LATENCY = "lt" ; private static final String ATT_ALL_THRDS = "na" ; private static final String ATT_GRP_THRDS = "ng" ; private static final String ATT_RESPONSE_CODE = "rc" ; private static final String ATT_RESPONSE_MESSAGE = "rm" ; private static final String ATT_RESPONSE_CODE_OLD = "rs" ; private static final String ATT_SUCCESS = "s" ; private static final String ATT_TIME = "t" ; private static final String ATT_TIME_STAMP = "ts" ; private static final String ATT_THREADNAME = "tn" ; public static String getVersion ( ) { } public boolean canConvert ( Class arg0 ) { } public void marshal ( Object obj , HierarchicalStreamWriter writer , MarshallingContext context ) { } protected void saveSamplerData ( HierarchicalStreamWriter writer , MarshallingContext context , SampleResult res , SampleSaveConfiguration save ) { } protected void saveResponseData ( HierarchicalStreamWriter writer , MarshallingContext context , SampleResult res , SampleSaveConfiguration save ) { } protected void saveRequestHeaders ( HierarchicalStreamWriter writer , MarshallingContext context , SampleResult res , SampleSaveConfiguration save ) { } protected void saveResponseHeaders ( HierarchicalStreamWriter writer , MarshallingContext context , SampleResult res , SampleSaveConfiguration save ) { } protected void saveSubResults ( HierarchicalStreamWriter writer , MarshallingContext context , SampleResult res , SampleSaveConfiguration save ) { } protected void saveAssertions ( HierarchicalStreamWriter writer , MarshallingContext context , SampleResult res , SampleSaveConfiguration save ) { } protected void setAttributes ( HierarchicalStreamWriter writer , MarshallingContext context , SampleResult res , SampleSaveConfiguration save ) { } protected void writeString ( HierarchicalStreamWriter writer , String tag , String value ) { } public Object unmarshal ( HierarchicalStreamReader reader , UnmarshallingContext context ) { } protected boolean retrieveItem ( HierarchicalStreamReader reader , UnmarshallingContext context , SampleResult res , Object subItem ) { String nodeName = reader . getNodeName ( ) ; if ( subItem instanceof AssertionResult ) { res . addAssertionResult ( ( ( AssertionResult ) ( subItem ) ) ) ; } else if ( subItem instanceof SampleResult ) { <START_BUG> res . addSubResult ( ( ( SampleResult ) ( subItem ) ) ) ; <END_BUG> } else if ( nodeName . equals ( SampleResultConverter . TAG_RESPONSE_HEADER ) ) { res . setResponseHeaders ( ( ( String ) ( subItem ) ) ) ; } else if ( nodeName . equals ( SampleResultConverter . TAG_REQUEST_HEADER ) ) { res . setRequestHeaders ( ( ( String ) ( subItem ) ) ) ; } else if ( nodeName . equals ( SampleResultConverter . TAG_RESPONSE_DATA ) ) { try { res . setResponseData ( ( ( String ) ( subItem ) ) . getBytes ( res . getDataEncoding ( ) ) ) ; } catch ( UnsupportedEncodingException e ) { res . setResponseData ( ( "Can't<seq2seq4repair_space>support<seq2seq4repair_space>the<seq2seq4repair_space>char<seq2seq4repair_space>set:<seq2seq4repair_space>" + ( res . getDataEncoding ( ) ) ) . getBytes ( ) ) ; } } else if ( nodeName . equals ( SampleResultConverter . TAG_SAMPLER_DATA ) ) { res . setSamplerData ( ( ( String ) ( subItem ) ) ) ; } else if ( nodeName . equals ( SampleResultConverter . TAG_RESPONSE_FILE ) ) { res . setResultFileName ( ( ( String ) ( subItem ) ) ) ; } else { return false ; } return true ; } protected void retrieveAttributes ( HierarchicalStreamReader reader , UnmarshallingContext context , SampleResult res ) { } protected void readFile ( String resultFileName , SampleResult res ) { } public SampleResultConverter ( ClassMapper arg0 ) { } }

Fix:
res . storeSubResult ( ( ( SampleResult ) ( subItem ) ) ) ;